1. Field of the Invention
This invention relates to a novel process for the synthesis of perfluoropyruvyl fluoride dimer.
2. Description of the Prior Art
Perfluoropyruvyl fluoride dimer has previously been prepared from the reaction of hexafluoropropene epoxide (HFPO) with benzophenone or benzaldehyde. This mode of preparation is described in Selman U.S. Pat. No. 3,321,517. The preparation involves heating a mixture of benzophenone (or benzaldehyde) and hexafluoropropylene epoxide in an autoclave at elevated temperatures (100.degree.-300.degree.C) under autogenous pressure to yield the perfluoropyruvyl fluoride dimer: ##EQU1## The quantities of materials are not critical as an excess of either reactant will merely remain unreacted.
The dimer is useful as a soil fumigant and insecticide and also as the intermediate for the synthesis of the monomer perfluoro-2-methylene-4-methyl-1,3-dioxolane (PMD). The latter, when polymerized, yields a clear polymer useful for making plastic contact lenses. The preparation of PMD from perfluoropyruvyl fluoride is described by Selman et al. U.S. Pat. No. 3,308,102, and its use in contact lenses, by Girard et al. U.S. Pat. No. 3,542,461.